Telephone instrument base



FIG. 1 is a left side, top and front view of a telephone instrument base showing my new design;

FIG. 2 is a front elevational view;

FIG. 3 is a right side elevational view; and

FIG. 4 is a bottom end elevational view;

FIG. 5 is a rear elevational view. 

The ornamental design for a telephone instrument base, as shown and described. 